1. Field of the Invention
This invention relates to lighting and, more particularly, to light emitting diode (LED) illumination as well as tubular lighting assemblies.
2. Background Art
Over the years various types of illuminating assemblies and devices have been developed for indoor and/or outdoor illumination, such as torches, oil lamps, gas lamps, lanterns, incandescent bulbs, neon signs, fluorescent bulbs, halogen lights, and light emitting diodes. These conventional prior art illuminating assemblies and devices have met with varying degrees of success.
Incandescent light bulbs create light by conducting electricity through a thin filament, such as a tungsten filament, to heat the filament to a very high temperature so that it glows and produces visible light. Incandescent light bulbs emit a yellow or white color. Incandescent light bulbs, however, are very inefficient, as over 98% of its energy input is emitted and generated as heat. A standard 100 watt light bulb emits about 1700 lumens, or about 17 lumens per watt. Incandescent lamps are relatively inexpensive and have a typical lifespan of about 1,000 hours.
Fluorescent lamps (light bulbs) conduct electricity through mercury vapor, which produces ultraviolet (UV) light. The ultraviolet light is then absorbed by a phosphor coating inside the lamp, causing it to glow, or fluoresce. While the heat generated by fluorescent lamps is much less than its incandescent counterpart, energy is still lost in generating the UV light and converting UV light into visible light. If the lamp breaks, exposure to mercury can occur. Linear fluorescent lamps are often five to six times the cost of incandescent bulbs but have life spans around 10,000 and 20,000 hours. Lifetime varies from 1,200 hours to 20,000 hours for compact fluorescent lamps. Some fluorescent lights flicker and the quality of the fluorescent light tends to be a harsh white due to the lack of a broad band of frequencies. Most fluorescent lights are not compatible with dimmers.
Light emitting diode (LED) lighting is particularly useful. Light emitting diodes (LEDs) offer many advantages over incandescent light sources, including: lower energy consumption, longer lifetime, improved robustness, smaller size, faster switching, and excellent durability and reliability. LEDs emit more light per watt than incandescent light bulbs. LEDs can be tiny and easily placed on printed circuit boards. LEDs activate and turn on very quickly and can be readily dimmed. LEDs emit a cool light with very little infrared light. LEDs come in multiple colors which are produced without the need for filters. LEDs of different colors can be mixed to produce white light. Other advantages of LEDs include: high efficiency; low energy consumption; higher outputs at higher drive currents; shock resistant with no filament, glass or tube to break, contain no toxic substances, hazardous mercury or halogen gases.
The operational life of some white LED lamps is 100,000 hours and 11 years of continuous operation. The long operational life of an LED lamp is much longer than the average life of an incandescent bulb, which is approximately 5000 hours. If the lighting device needs to be embedded into a very inaccessible place, using LEDs would minimize the need for regular bulb replacement. With incandescent bulbs, the cost of replacement bulbs and the labor expense and time needed to replace them can be significant especially where there are a large number of incandescent bulbs. For office buildings and high rise buildings, maintenance costs to replace bulbs can be expensive and can be substantially decreased with LED lighting.
An important advantage of LED lighting is reduced power consumption. An LED circuit will approach 80% efficiency, which means 80% of the electrical energy is converted to light energy; the remaining 20% is lost as heat energy. Incandescent bulbs, however, operate at about 20% efficiency with 80% of the electrical energy is lost as heat. Repair and replacement savings can be significant, as most incandescent light bulbs burn out within a year and require replacements whereas LED light bulbs can be used easily for a decade without burning out.
LED light (lighting) bars are considered to be much better than incandescent lights. Incandescent light bulbs do not last for a long time and the filament burns out. An LED light bar consumes less energy and has a longer life. LED light output is much brighter than that of an incandescent light bulb.
An assortment of colors and flash patterns are available with LED light bars for emergency vehicles such as police cars, fire trucks and ambulances. Emergency vehicles such as ambulances and police cars prefer mounting a LED light bar on the top for easy recognition and visibility. LED light bars can be used on the interior as well as on the exterior of the emergency vehicles as it emits sufficient light even in the darkest of areas. Furthermore, since the heat produced by LED light bars is small, it won't adversely affect the interior of the vehicle.
LEDs are used in applications as diverse as aviation lighting, traffic signals and automotive lighting such as for brake lights, turn signals and indicators. LEDs have a compact size, fast switching speed and good reliability. LEDs are useful for displaying text and video and for communications. Infrared LEDs are also used in the remote control units of many commercial products including televisions, DVD players and other domestic appliances.
Solid state devices such as LEDs have excellent wear and tear if operated at low currents and at low temperatures. LED light output actually rises at colder temperatures (leveling off depending on type at) around-30° C.). Consequently, LED technology may be a good replacement for supermarket freezer lights and will often last longer than other types of lighting.
Large-area LED signs and displays are used as stadium displays and as decorative displays. LED message displays are used at airports and railway stations, and as destination displays for trains, buses, trams, and ferries.
With the development of efficient high power LEDs, it has become more advantageous to use LED lighting and illumination. High power white light LED lighting is useful for illumination and for replacing incandescent and/or fluorescent lighting. LED street lights are used on posts, poles and in parking garages. LED's are now used in stores, homes, stage and theaters, and public places. Furthermore, color LED's are useful in medical and educational applications such as for mood enhancement. In many countries incandescent lighting for homes and offices is no longer available and building regulations require new premises to use LED lighting.
Conventional prior art LED lighting which is powerful enough for room lighting, however, is relatively expensive and requires more precise current and heat management than fluorescent lamp sources of comparable output. Furthermore, conventional LED lighting can have a higher capital cost than other types of lighting and LED light tends to be directional with small areas of illumination. Moreover, conventional LED luminaries suffer from drawbacks due to a lack of lumen output and less than desirable light dispersion. Individually and combined, these aspects of conventional LED lighting can detract from efficient utilization of LED luminaries.
One problem that has plagued the lighting industry is associated with how conventional, elongate, tubular lighting components are operatively mounted through end connectors. As described in greater detail below, conventional tubular lighting, having a source of illumination that is an LED, a gas-discharge lamp that uses fluorescence to produce visible light, or another known source on, or within, a tubular body, typically utilizes a bi-pin/2-pin means on the tubular body that mechanically supports the body in an operative state and effects electrical connection of the illumination source to a power supply.
Typically, the body has a cylindrical shape with a central axis. The pins making up the bi-pin means project in cantilever fashion from the body ends. The body must be situated in a first angular orientation to direct the pins into spaced connectors on a support/reflector and is thereafter turned to effect mechanical securement and electrical connection.
Installation requires a precise initial angular orientation of the body and subsequent controlled repositioning thereof to simultaneously seat the pins at the opposite ends of the body. Often one or more of the pins are misaligned during this process so that electrical connection is not established. The same misalignment may cause a compromised mechanical connection whereupon the body may escape from the connectors and drop so that it is damaged or destroyed.
Further, the connectors on the support/reflector are generally mounted in such a fashion that they are prone to flexing. Even a slight flexing of the connectors on the support might be adequate to release the pins at one body end so that the entire body becomes separated. Furthermore, the conventional bi-pin means for mechanically holding the body in place, while also allowing power to be distributed to the illumination source, was created for very lightweight fluorescent lighting and not designed for LED tubular lighting that has additional weight due to the required heat sink and PCB boards. The weight of the body by itself may produce horizontal force components that wedge the connectors on the support/reflector away from each other so that the body becomes precariously situated or fully releases.
A still further problem with this type of lighting configuration, particularly with an LED illumination source, is that the end connectors joined to the body are by their nature difficult to consistently assemble. Typically, the manufacturing process will involve steps of soldering conductive components on, and cooperating between, the end connectors and illumination source. Wires are commonly used in these designs, with the ends thereof soldered during the assembly process. If the conductive components are not properly connected, the system may be inoperable. Soldered connections are also prone to failing when subjected to forces in use. Generally, it is difficult to maintain a high level of quality control, regardless of the care taken in assembling these types of components. Aside from the quality issue, the assembly steps that involve the electrical connection of the conductors are inherently time consuming and may require relatively skilled labor, and/or expensive automated systems. Disassembly of such lamps presents similar difficulties and expense. As a result of these difficulties associated with assembly and disassembly, refurbishing such lamps to replace defective or worn out components is difficult to justify economically. In most cases, the entire lamp assembly will simply be discarded and replaced with a new lamp assembly, and as a result, lamp components that have significant useful life remaining are wasted.
Still another problem in the lighting industry are the difficulties and costs associated with proper design and control of emergency lighting circuits. Emergency lighting systems are required by a myriad of municipal, state, federal or other codes and standards. These systems are intended to automatically supply illumination to designated areas and equipment in the event of failure of the normal power supply, to protect people and allow safe egress from a building, and to provide lighting to areas that would aid rescuers or repair crews. These systems are typically required by regulation to be available within a short time (e.g. 10 seconds) after failure of normal power, and emergency circuits must be physically separated from all other circuits all the way to the terminations and the source. Other standby systems, although not legally required, may be desirable to provide lighting to prevent discomfort or serious damages to a product or process.
The proper design and control of emergency lighting circuits in compliance with the many standards and codes that may apply to a given site installation has long presented difficult challenges for manufacturers, systems integrators and electricians and engineers. As a result, a number of approaches to the designing emergency or standby lighting circuits have been attempted. One known approach involves providing a number of emergency-only luminaires dedicated to providing minimum illumination levels and powered by a dedicated emergency breaker panel fed from a generator or uninterruptable power supply (UPS). An uninterruptible power supply is an electrical apparatus that provides emergency power to a load when the input power source, typically mains power, fails. A UPS differs from an auxiliary or emergency power system or standby generator in that it will provide near-instantaneous protection from input power interruptions, by supplying energy stored in batteries or a flywheel. Regardless of the source of back-up power, the emergency fixtures remain dark when normal power is present, and are energized when the control circuit detects failure of the normal power supply. This approach entails the potentially high cost of the emergency system equipment and may be visually unappealing as result of excess luminaries which are not illuminated during normal conditions.
Another approach involves self-contained battery pack emergency lights, which contain a battery, a charger, and a load control relay. These units are connected to normal power, which provides a constant charging current for the battery. During a power failure, the load control relay energizes the emergency lights. This approach avoids the need to deploy physically separated emergency circuits, but is typically implemented in aesthetically unpleasing forms resembling a car headlight battery pack unit.
Still another approach uses the same light fixture for both normal an emergency use. The lights are fed using the normal breaker panel and wall mounted switch during normal operation. When power fails, an emergency transfer circuit transfers the breaker panel feed to an emergency power source, and bypasses the wall switch to force the load on the lights regardless of the wall switch position. Although such systems offer aesthetic advantages, they are expensive and complex to design and install. Other known approaches suffer similar drawbacks.
It is, therefore, desirable to provide an improved LED illuminating assembly, which overcomes some, if not all, of the preceding problems and disadvantages.